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Algebra Level 2

When Sarah was writing up her Final Year Project, she used 20 pages each of 55 lines and each such line consists of 65 characters. Wanting to be environmentally friendly, she decided instead to use pages each with 65 lines such that each line consists of 70 characters.

What is the approximate percentage reduction in the number of sheets?

5 30 35 20

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23 solutions

Test User
Feb 19, 2014

Simply, we note that the number of characters in the essay is

20 s h e e t s 55 l i n e s s h e e t 65 c h a r a c t e r s l i n e = 71500 c h a r a c t e r s 20 \ sheets * 55 \frac{lines}{sheet}* 65 \frac{characters}{line} = 71500 \ characters

Now, after reformatting we have

71500 c h a r a c t e r s 1 l i n e 70 c h a r a c t e r s 1 p a g e 65 l i n e s = 15.71 c h a r a c t e r s 20 71500 \ characters * \frac{1 \ line}{70 \ characters} * \frac{1 \ page}{65 \ lines} = 15.71 \ characters \approx \boxed{20}

units are of importance ...its 15.71 pages... which is approx. 80% of 20 pages therefore reduction in pages is 20%.

Arjun Singh Yadav - 7 years, 3 months ago

15.71 ~ 16 , Now (20-16)/20 * 100 = 20%

Jayesh Narayan - 7 years, 3 months ago

15.71 pages maybe..

Eka Kurniawan - 7 years, 3 months ago

20sheets * 55 lines * 65 Charcters= n sheets * 65 lines 8 70 characters n sheets= (20 * 55 * 65)/ (65 * 70) = 15.71 characters

Supriya Kattimani - 7 years, 3 months ago

Something was wrong with the question

anas salhi - 7 years, 2 months ago

Good Approach !

Abhishek Singh - 7 years, 3 months ago

nice 1

Subhrajyoti Nayak - 7 years, 3 months ago

15.71 pages ,almost 16 pages after contraction 20-16=4 pages saved 4/20 = 20%

Yaman Rajab - 7 years, 3 months ago

20 page coz there is no limit of characters

Awais Instine - 7 years, 3 months ago

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there is a limit .....the essay is written once and fixed...

Arjun Singh Yadav - 7 years, 3 months ago

20%

Kanishak Bishnoi - 7 years, 3 months ago

16 pages means 20%

Govind UR - 7 years, 3 months ago

15.7 is my answer

Minhal Zaidi - 7 years, 3 months ago

hw to calculate this one

amulu kutima - 7 years, 3 months ago

oh I was near to the result but sily mistake at end

abhishek daberao - 7 years, 3 months ago

The answer is exactly 20% as 15.71 pages means 16 pages used. So 100 - (16/20 x 100) = 20%

Amlan Mishra - 7 years, 3 months ago

isn't there difference between between sheets and pages. Sheet is a whole paper. While pages are 2 per sheet.

Chitranshu Vashishth - 7 years, 3 months ago

Dimensional analysis.

Marchan Sy - 7 years, 3 months ago
Abhyuday Bhatt
Feb 27, 2014

FIRST YOU HAVE TO FIND TOTAL NUMBER OF WORDS IN FIRST CONDITION I.E. 20 SHEETS * 55 LINES * 65 WORDS= 71500 WORDS

NOW THIS IS ALSO THE NUMBER OF WORDS IN SECOND CONDITION NOW THE NUMBER OF SHEETS IN SECOND CONDITION IS 71500 WORDS / 70 WORDS /65 LINES= 15.714286

NOW BECAUSE THE OF SHEETS IS 15.714286 IT MEANS 1 MORE SHEET WILL BE USED AFTER 15 SHEETS I.E. 15.714286 MUST BE CONSIDERED AS 16 SHEETS

NOW THE PERCENTAGE REDUCTION IS

(20-16)/20*100 =20

EASEY PEASEY :)

reduction in pages = 20 - {(20x65)/70} which equals to 4.2857, and percent reduction = 4.2857x100/20 and the answer 21.4286 %

Harshal Khachane
Mar 8, 2014

-first case:Total no of chars=20x55x65;

2nd case: total no of chars=sheetsx65x70;

characters will be same in both the case;

20x55x65=sheetsx65x70;

sheets=integer(15.7)=16;

16 is 80% of 20 sheets;

20% sheets are saved;

Book 1

55 lines x 65 characters = 3575 characters per page. So, For 20 pages, 3575x20= 71500 characters

Book 2

65 lines x 70 characters = 4550 characters per page. So, for 'x' pages, 4550 x 'x'=71500 characters So, No. of pages=71500/4550= 15.71 pages

Reduction Percentage= ((20-15.71)x100)/20

21.45%  ≈ 20%

Tirthankar Ghosh
Mar 30, 2014

Find the total number of characters and then divide by 65 x 70. The answer will be 11/14. So the reduction in pages will 3/14. Therefore, 3/14 x 100 % = 21.4 which is closest to 20.

Maheswara Murthy
Mar 24, 2014

Here first given that 20 pages 55lines 65char=71500char and N-pages 65lines 70char=71500char then N-pages=71500char (1/65lines) (1/70char)=15.714 ~=20

Hendro Ong
Mar 23, 2014

Because the question is not asking exact number of paper saved, so we just have to make a simple calculation of percentage for this problem.

% paper reduction = (1 - 55/65 x 65/70) x 100% = (1- 55/70 )x 100% = 21.42 % (approx 20%)

she 20 pages of 55 lines of 65 characters. so the total number of characters would be 20 55 65 which is equal to 71500 characters. let the number of new pages used be x. it consists of 65 lines which can contain 70 characters. so the eq becomes

x 65 70=71500 (as we know the total number of characters)

x=71500/4550=15.714. so she used 16 pages. now we have to find the reduction of pages.

using proportion: 100:20::x:16

100*16=20x

x=1600/20=80%

and so the reduction percentage would be 20%

Fahmid Sketched
Mar 11, 2014

Page reduction percentage same as character reduction percentage.

  • Before, 55*65 = 3575 characters per page.
  • Now, 70*60 = 4550 characters per page.

Converting to percentage, that's ~80%. 100-80 = ~20% Reduction.

Muhamed Medo
Mar 6, 2014

no of characters she wrote = 65 55 20=71500 no of sheets that has 65 lines = 71500/(65*70)= 15.714 app.=20

Muhamed Medo
Mar 6, 2014

number of characters = 20 55 65=71500 character number of largest sheets = 71500 / (65*70) = 15.714 approximetly = 20 (the answer)

David Jiang
Mar 5, 2014

The easiest way to calculate this rather than brute force is to realize that the proportion is the same as the reduction. Thus the proportion of NEW PAGES to OLD PAGES has the 20, and the 65's cancel out. You are left with 55 pages to 70 pages which is about 80%. Reverse that for a 20% reduction

Tanveer Hussain
Mar 4, 2014

(55 65/65 70)*100=78.5714 100-78.5714=21.4

In first case, let x be the total number of characters then x = 20 * 55 * 65 => 20 = x / 55 * 65 --------------equation(1)

In second case let no of pages be y but the number of characters in the essay will be same i.e. x then x = y * 65 * 70 => y = x / 65 * 70 ---------equation(2)

equation(2) / equation(1) y / 20 = (x / 65 * 70) / (x / 55 * 65) y / 20 = 55 / 70 y = 110 / 7 then % decrease in pages = {[20 - (110 / 7)] / 20} * 100 = 21.4 % = 20%(approx).

Krishna Garg
Mar 3, 2014

In one page of 55 lines and 65 characters are used that is 3575 in each page completed in 20 no of pages. thus total 71500. with 65 lines and 70 characterrs that is 4550 will be covering 71500 in 15.7 ( almost 16 pages) Now, she saves 20-16 =4 pages out of 20 that is 4/20 X100 =20 % Ans.

K.K.GARG,INDIA

Rizky Riman
Mar 2, 2014

20 × 55 × 65 = x × 65 × 70 20 \times 55 \times 65 = x \times 65 \times 70 x = 15 , 7 16 x = 15,7 ~ 16 16 20 × 100 p e r c e n t = 80 p e r c e n t \frac{16}{20} \times 100 percent = 80 percent 100 p e r c e n t 80 p e r c e n t = 20 p e r c e n t 100 percent - 80 percent = \boxed{20 percent}

Khadijat Oyeleye
Mar 1, 2014

This is how I did it:

20 sheets x 55 lines x 65 characters= 71500

20 sheets x 65 lines x 70 characters= 91000

91000-71500=19500

19500/100000=19.5/100 which is roughly equivalent to 20%

Ehtisham Padda
Mar 1, 2014

first calculate the number of pages in case of 65 lines and 70 characters.... then u'll easily calculate reduction percentage;)

Increase in lines by a factor of 65/55 = 13/11. Increase in characters per line by a factor of 70/65 = 14/13. Their product is 14/11, so the number of pages decreases by a factor of 11/14 which leaves about 80% of the original number of pages, a 20% reduction.

Arijit Banerjee
Feb 27, 2014

55 65 20 = 70 65 x (where x is number of pages used) x=15.71, now reduction in page = 4.29 and % of reduction is 21.45% and here nearest answer given is 20% so answer is 20%!

I gave " * " but it did not show up when I was about to post it. There will b * sign after every two nos.

Arijit Banerjee - 7 years, 3 months ago

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* doesn't appear, because it is used in markdown to denote italics or bold.

You can refer to the Math formatting guide for more details.

Calvin Lin Staff - 7 years, 3 months ago

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thanks!

Arijit Banerjee - 7 years, 3 months ago
Arijeet Satapathy
Feb 27, 2014

Number of sheets used in environment friendly way:206555=x6570=>x=16 Finally reduction percentage: (20-16)/20*100=20

Kiran Kumar
Feb 27, 2014

She saved 3 and a half pages out of 20 pages. That is 18 % which is approximately 20%

Sarah used 20 pages each of 55 lines and each such line consists of 65 characters. No of Characters Sarah written is 65 Characters x 55 Lines x 20 Pages = 71,500/- Characters .

Now Sarah decides to use pages each with 65 lines such that each line consists of 70 characters.
Number of sheets Sarah will use » 71,500 Characters / (70 Characters x 65 Lines) = 15.71 Sheets or 16 Sheets.

Percentage reduction in the number of sheets » (20 Sheets – 16 Sheets) / 20 Sheets = 20%

CA Sudharsan KG - 7 years, 3 months ago

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